Diagnosis

Laennec's stethoscope, France, 1815-1825

Reading chest x-rays

Doctor, what’s wrong with me?’ The first step towards successfully treating a complaint is finding out what you are suffering from. Greek doctors coined the expression ‘diagnosis’ for this process: ‘the means of distinguishing or recognising’. Medical practitioners use various methods and tools to diagnose. These include their senses, the patient’s descriptions of his or her symptoms, and medical instruments or tests to investigate causes for the complaint. Arriving at a diagnosis is like being a detective. Medical practitioners detect clues and interpret them correctly. It is not surprising that a medical man, physician Joseph Bell, was the inspiration for Sherlock Holmes, the world’s most famous literary detective.

Healers throughout history and across cultures used different diagnostic methods. Early civilisations used magical practices such as divination, whereas medieval Europeans used astrology. Medical traditions worldwide including Ayurveda, Unani Tibb and Traditional Chinese Medicine interpret features of the patient’s body such as the pulse and the urine. Doctors now use lots of diagnostic tools and techniques in their ’detective work‘. These include instruments such as microscopes and stethoscopes which augment the senses; technologies such as X-ray or ultrasound machines which make the inside of the body visible; or tests to reveal germs or genetic defects.

Definitions of disease

The process of diagnosis still causes problems despite the availability of these and other techniques. Doctors must firstly agree on the definition of a disease. What are the symptoms of a disease? Does a condition count as a disease in the first place? Weekly ‘Bills of Mortality’ listed deaths and their causes in early modern London. They show examples of conditions that no longer count as diseases. Fever is now a symptom rather than a disease. Historians are unsure what ‘rising of the lights’ was, but early modern Londoners knew it as a deadly disease!

Problems of interpretation

Interpreting clues may be difficult even if doctors agree on the definitions of a disease. How can doctors understand a patient’s description of his or her very personal experience of pain? Instruments and tests obtain additional information, but the interpretation problem remains. In the 1960s, Alvan Feinstein, Professor of Medicine at Yale University, investigated how doctors judged heart sounds to be normal or abnormal. He found some practitioners paid attention mostly to the pitch of the sound, and others to the duration or change with posture. Assumptions about diseases also cause diagnosis problems. Some diseases are considered ‘male’ or ‘female’ diseases, and this shapes doctors’ perceptions. Heart diseases are commonly ‘male’ complaints. Researchers found women are less likely to be diagnosed correctly if they suffer a heart attack.

Authority and conflict

Different interpretations of symptoms result in conflicting diagnoses. This causes problems of authority. Many people can access medical information on the internet and diagnose themselves. Alternatively, two medical practitioners may interpret your symptoms differently. Whose diagnosis do you trust? Technology cannot always provide a solution, especially if different tests or examinations produce contradictory results.

Consequences of diagnosis

Being diagnosed with a disease can have social, financial and legal consequences. In some health-care systems your diagnosis determines how much compensation you get from medical insurance. Being labelled with a disease can shape a person’s self-perception, especially if a stigma is attached. Diagnosis can also affect your position in society and personal rights. Victorian England was gripped by ‘lunacy scares’. This was the fear women could be declared insane by their husbands or families and subjected to ‘wrongful confinement’ in asylums. In 1851 an American doctor argued enslaved Africans were afflicted with a compulsion to escape called ‘drapetomania’. This ‘medicalisation’ of Africans’ responses to enslavement was used by white supporters of slavery. They argued captive Africans should never be treated too well or they would catch this disease.

S A Cartwright, ‘Report on the diseases and physical peculiarities of the Negro race’, The New Orleans Medical and Surgical Journal (1851), pp 691-715

A B Davis, Medicine and Its technology: An Introduction to the History of Medical Instrumentation (Connecticut, 1981)

H Schmidgen, 'Pictures, Preparations, and Living Processes: The Production of Immediate Visual Perception (Anschauung) in late-19th-Century Physiology', Journal of the History of Biology, 37 (2004), pp 477-513